The subject invention relates to processes of making vinyl polymer emulsion products. More particularly, it relates to substantially external surfactant-free processes of making vinyl polymer emulsion products.
Vinyl polymer emulsion products are well known and have been used extensively. They have found particular use in the coatings arts. Polymeric emulsions have become more prevalent in recent years due to the water base nature of the emulsions. Such emulsions necessarily have a low organic solvent content and thus avoid many of the environmental and cost problems associated with organic solvents. Typical prior art processes for making vinyl polymer emulsions have involved the use of an external surfactant to aid in dispersing the vinyl polymer in water. However the external surfactants used in the process are carried throughout the process and into coating compositions formulated with the emulsions. Films formed from such coating compositions still contain the external surfactant. This has proved disadvantageous due to the fact most surfactants are water sensitive and therefore the resultant film is also water sensitive. Additionally the surfactant is free to leach out. This proves to be a disadvantage whenever the coating composition is used for the internal coating of containers. Thus the leaching out of the surfactant into the container's contents is particularly troublesome.
There is accordingly a need for a process for making vinyl polymer emulsion products without the use of an external surfactant. Such objective is met by the herein disclosed and claimed process.
As used herein all percentages and ratios are by weight unless otherwise indicated.